This invention pertains to a barrier, which is intended to intercept a crashing airplane before it reaches a target. The barrier comprises an array of spaced towers, each of which is several hundred feet tall, and further comprises guys interconnecting each tower with another tower, with ground anchors, or with both.
Recent attacks on the World Trade Center in New York, N.Y., and on the Pentagon have heightened concerns that power plants, chemical plants, and other similar and dissimilar targets might be highly vulnerable to airplanes that could crash into such targets, either accidentally or deliberately. A concept has been suggested, by another or others, that a barrier comprised of spaced poles, pylons, or towers, if constructed and situated properly, might intercept a crashing airplane before it reached a target.
This invention improves on the aforenoted concept that a barrier comprised of spaced poles, pylons, or towers, if constructed and situated properly, might intercept a crashing airplane before it reached a target. This invention can be suitably embodied in a barrier wherein each tower is several hundred feet tall.
According to a first aspect of this invention, the barrier further comprises a first set of guys interconnecting each tower of the array with at least one other tower of the array, whereby forces imparted by an airplane crashing into a given tower of the array are distributed by guys of the first set to the tower or towers interconnected with the given tower. According to a second aspect of this invention, the barrier further comprises a second set of guys extending away from the target, extending downwardly, and connecting the towers to ground anchors, whereby forces imparted by an airplane crashing into a given tower of the array are distributed by guys of the second set to the ground anchors connected to given tower. The first and second aspects of this invention can be advantageously combined.
Preferably, each tower comprises a trusswork, which includes steel tubes. Preferably, each tube is filled at least partially with a cementitious material, such as grout, which is pumped into said tube and which is allowed to cure. Preferably, each tube comprises plural sections, which have end flanges and which are bolted to one another at the flanges. Preferably, the flanges contacted by the cementitious material being pumped have means, which may comprise gaskets, to prevent the cementitious material from being extruded between the flanges contacted by the cementitious material before the cementitious material has cured.